<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0 auto;
        }

        .w {
            width: 1000px;
        }

        .head {
            height: 200px;
            background-color: pink;
        }

        .banner {
            margin-top: 10px;
            height: 1200px;
            background-color: purple;
        }
        
        .bottom {
            margin-top: 10px;
            height: 1400px;
            background-color: peru;
        }
        
        .tip {
            top: 300px;
            right: 0;
            position: absolute;
            width: 70px;
            height: 120px;
            background-color: blue;
            color: white;
        }

        .goback {
            display: none;
        }
    </style>
    <script src="./js/ex003仿淘宝固定侧边栏.js"></script>
</head>
<body>
    <div class="head w">head</div>
    <div class="banner w">banner</div>
    <div class="bottom w">bottom</div>
    <div class="tip">
        <div class="goback">返回顶部</div>
    </div>
</body>
</html>